GE EPM 9650/9800 manual Receive and Transmit Buffers Port

	Port Control Pointers
Port	ReceiveIn	ReceiveOut	TransmitIn	TransmitOut
Port 4 (I/O)	41733	41734	41735	41736
Port 3	41737	41738	41739	41740
Port 2	41741	41742	41743	41744
Port 1 (232/485)	41745	41746	41747	41748
Diagnostic Port	41749	41750	41751	41752

ReceiveIn indexes the location where the next received character will be placed in the Receive Buffer by the interrupt routine. ReceiveOut indexes the location where the next character should be removed from the Receive Buffer by the parsing routine. TransmitIn indexes the location where the next character to be transmitted should be placed by the communication generation routine. TransmitOut indexes the location of the next character to be transmitted by the interrupt

routine.

The Receive Buffer is empty if RecIn = (RecOut+1) Mod 512. The Receive Buffer is full if RecIn = RecOut. The Transmit Buffer is empty if TrmIn = TrmOut. The Transmit Buffer is full if TrmOut = TrmIn+1) Mod 512.

When a port is locked, its pointers may be modified by the locking port.

When a TransmitIn Register is written, that causes the interrupt routines to transmit characters in the Transmit Buffer from TransmitIn to TransmitOut.

Receive and Transmit Buffers (41985-44544):These Registers, when read, return the contents of the appropriate Receive and Transmit Buffers. Each buffer is 256 Registers (512 bytes) long. The order of the buffers is:

	Receive and Transmit Buffers
Port	Receive	Transmit
Port 4 (I/O)	41985-42240	43265-43520
Port 3	42241-42496	43521-43776
Port 2	42497-42752	43777-44032
Port 1 (232/485)	42753-43008	44033-44288
Diagnostic Port	43009-43264	44289-44544

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